1. Field of the Invention
The present invention relates in general to a finger hole drilling machine for bowling balls and, more particularly, to a structural improvement in such a finger hole drilling machine for precisely drilling the finger holes on a plurality of bowling balls of a bowler at the same positions and at the same drilling angles, so that the finger holes of the bowling balls are identified with each other.
2. Description of the Prior Art
In order to drill the finger holes on a bowling ball using a typical finger hole drilling machine, the bowling ball is marked with finger hole drilling position marks on its spherical surface and tightly clamped at its opposed sides by conventional clamping means. In this state, the desired finger holes are formed on the bowling ball by drilling the bowling ball at the every finger hole drilling position using the typical drilling machine.
However, the above finger hole drilling method has a problem that it is difficult to precisely center the drill of the drilling machine to each of the finger hole drilling position marks on the spherical surface of the bowling ball. Particularly, the above problem caused in the typical finger hole drilling method will become worse when a plurality of bowling balls of a bowler need to be identically provided with their finger holes at the same positions and at the same drilling angles.
That is, bowlers regardless of professional bowlers and amateur bowlers generally have a plurality of bowling balls, that is, practice balls and game balls. The bowling balls of bowlers have their finger holes at different positions due to difference of finger and hand sizes of the bowlers.
In the plurality of bowling balls of a bowler regardless of practice balls and game balls, the finger holes need to be identically drilled on all of the balls at the same positions and at the same drilling angles in order to fit the specified finger and hand sizes, that is, lengths of thumb and of fingers and area of palm of the hand of the bowler. That is, in the plurality of bowling balls of a bowler, the finger holes should be drilled on all of the bowling balls, so that the finger hole depths, the drilling angles and intervals between the finger holes are identified with each other in all the balls of the bowler. When the identity of the finger holes of the bowling balls owned by a bowler is achieved, the bowler will achieve good results in exercise and game.
However, the typical finger hole drilling method, which method comprises the steps of marking the finger hole drilling position marks on the spherical surfaces of the balls and of tightly clamping at opposed sides of each ball using conventional clamping means and of centering the drill to the marks and drilling the finger holes on each bowling ball, nearly fails in precisely drilling the finger holes on each ball and wastes time in clamping the balls. Furthermore, the above drilling method scarcely provides the identity of the finger holes of the balls owned by a bowler, thus to fail in letting the bowler achieve good results in bowling exercise and in bowling game.